Material pocket

MATERIALS Pocket watch with plastic crystal, small screw, electric wire, battery, electric blasting cap. 

A. Fickel, SiC Materials, in Refractory Materials - Pocket Manual, G. Routschka (Ed.), Vulkan Verlag, Essen, 1997, pp. 74-80. 

Fickel, A. (1997) in Refractory Materials Pocket Manual (ed. G. Routsdika), Vulkan-Verlag Essen, pp. 74-80. 

Rheometers are used in a much larger frequency range than DMA, for a large variety of materials, from liquids to soft solids. Their configurations are plate-plate and cone-plate, whereas torsion and tension attachments are optional. Dynamic mechanical analyzers perform only oscillatory experiments on load-bearing samples (i.e., those that have a shape with well-defined dimensions, such as films, fibers, or bars). The samples can be fixed in specific attachments, such as tension, bending, shear, or compression. A new attachment has been developed for DMA that is intended for non-self-supporting samples—a material pocket (Pinheiro and Mano 2009). The material pocket behaves elastically over the studied temperature... 

Warren J. Frederick, Royall G. Paul, Butterworth J. Peter, and Ellis L. Peter. Immersion mode material pocket dynamic mechanical analysis (IMP-DM A) A novel tool to study gelatinization of purified starches and starch containing-plant materials. Carbohydr. Polym. 90 no. 1 (2012) 628-636. 

Bolton, W., Engineering Materials Pocket Book, CRC Press, Boca Raton, FL, 1989. 

Powder samples are not usually measured by DMA due to difficulty in containing them. However, a recent innovation by Triton Technology Ltd [15] enables such samples to be analysed in a simple manner. The Materials Pocket for powders and films consists of a foldable metal sheet (see Figure 4.20). Alternatively measurements are possible in compression, but this geometry never has the sensitivity of normal bending modes. 

Frequently, Tg detection is a requirement in pharmaceutical and food studies, but it is difficult to obtain solid bar samples. The greater sensitivity of DMA over DSC offers excellent Tg determination, especially where only small amounts of amorphous material are present. To use the Material Pocket, 10-50 mg of sample is poured into the V-shaped trough and the pocket is tightly closed with a pair of phers or a small vice. The absolute values of the storage modulus E ) and loss modulus E") will not be quantitative, due to the stiffness of the metal Material Pocket. However, during a 7 process the change of each of these parameters is quantitative. 

Figure 4.20 shows a comparison of tan 8 data for a poly(styrene) powder analysed in a Material Pocket with a poly(styrene) bar sample (4 x 5 x 10 mm ). Whilst the magnitudes differ by a factor of 10, the temperature information and the glass transition detection are almost identical. The lower tan 8 is due to the effective dilution of the signal by the stiffness of the Material Pocket. 

Figure 4.21 Amorphous and crystalline lactose measured in Material Pocket.

A more recent approach using DMA makes use of a materials pocket for powders, which is mounted in a flexural mode. This provides an easier method of determining the Tg of a powder, and whilst modulus values are non-quantitative, measurement of amorphous... 

Mechanical, as opposed to viscosity, measurements on fats are comparatively rare. Often this is due to the brittle nature of the materials, for example chocolate. However, one approach is to observe the major transitions using the Triton materials pocket or constrained layer damped beam method. At present, however, absolute values of moduli cannot be obtained. Nevertheless, transitions between polymorphs in cocoa butter were measurable. 

Copper s melting point is relatively high (1,083 °C), but its creep, the continuous deformation when subject to constant stresses, already becomes pronounced at 120 °C, and the metal s tensile strength is no more than 170 MPa see Bolton, W. 1989. Engineering Materials Pocket Book. Boca Raton, Fla. CRC Press, pp. 98, 100. 

When we consider sources of methane we have to add old methane methane that was formed millions of years ago but became trapped beneath the earth s surface to the new methane just de scribed Firedamp an explosion hazard to miners oc curs in layers of coal and is mostly methane Petroleum deposits formed by microbial decomposi tion of plant material under anaerobic conditions are always accompanied by pockets of natural gas which IS mostly methane... 

Occlusions, which are a second type of coprecipitated impurity, occur when physically adsorbed interfering ions become trapped within the growing precipitate. Occlusions form in two ways. The most common mechanism occurs when physically adsorbed ions are surrounded by additional precipitate before they can be desorbed or displaced (see Figure 8.4a). In this case the precipitate s mass is always greater than expected. Occlusions also form when rapid precipitation traps a pocket of solution within the growing precipitate (Figure 8.4b). Since the trapped solution contains dissolved solids, the precipitate s mass normally increases. The mass of the precipitate may be less than expected, however, if the occluded material consists primarily of the analyte in a lower-molecular-weight form from that of the precipitate. 

However, all the receptors hitherto discussed are monomolecular species which possess a monomolecular cavity, pocket, cleft, groove or combination of it including the recognition sites to yield a molecular receptor—substrate complex. They can be assembled and preserved ia solution although there are dependences (see below). By way of contrast, molecular recognition demonstrated ia the foUowiag comes from multimolecular assembly and organization of a nonsolution phase such as polymer materials and crystals. 

J. G. Baet2, Characterisation of Advanced Solid Pocket No ffe Materials (SAMSO-TR-75-301), Air Eorce Rocket Propulsion Laboratories, Edwards AEB, Calif., Dec. 1975. 

The gas phase in a cellular polymer is distributed in voids, pores, or pockets called cells. If these cells are intercoimected in such a manner that gas can pass from one to another, the material is termed open-ceUed. If the cells are discrete and the gas phase of each is independent of that of the other cells, the material is termed closed-ceUed. 

Supports. The spaciag of supports is governed by the hot allowable stress of the piping materials stabiUty, ia the case of large-diameter thin-wall pipe deflection to avoid sagging or pocketing and the natural frequency of the unsupported length to avoid susceptibiUty to undesirable vibration. 

Rotary V lve Feeders. Devices known as rotary valve feeders are commonly used for circular or square configured outlets. These are particularly useful when discharging materials to a pneumatic conveying system where a seal is required to prevent air flow through the hopper outlet. The discharge rate is set by the speed of rotation of the vanes or pockets of the valve. 

To complete the assembly of a cell, the interleaved electrode groups are bolted to a cov er and the cover is sealed to a container. Originally, nickel-plated steel was the predominant material for cell containers but, more recently plastic containers have been used for a considerable proportion of pocket nickel-cadmium cells. Polyethylene, high impact polystyrene, and a copolymer of propylene and ethylene have been the most widely used plastics. 

Other Cells. Other methods to fabricate nickel—cadmium cell electrodes include those for the button cell, used for calculators and other electronic de dces. Tliis cell, the construction of which is illustrated in Figure is commonly made using a pressed powder nickel electrode mixed with graphite that is similar to a pocket electrode. Tlie cadmium electrode is made in a similar manner. Tlie active material, graphite blends for the nickel electrode, are ahnost the same as that used for pocket electrodes, ie, 18% graphite. 

Cell Construction. Nickel—2iac batteries are housed ia molded plastic cell jars of styrene, SAN, or ABS material for maximum weight savings. Nickel electrodes can be of the siatered or pocket type, however, these types are not cost effective and several different types of plastic-bonded nickel electrodes (78—80) have been developed. 

Presence of Solids When a pump is required to pump a hquid containing suspended solids, there are unique requirements which must be considered. Adequate clear-liquid hydraiilic performance and the use of carefully selected materials of construction may not be all that is required for satisfacdoiy pump selection. Dimensions of all internal passages are critical. Pockets and dead spots, areas where solids can accumulate, must be avoided. Close internal clearances are undesirable because of abrasion. Flushing connections for continuous or intermittent use should be provided. 

Labyrinth seals are simple to manufacture and can be made from conventional materials. Early designs of labyrinth seals used knife-edge seals and relatively large chambers or pockets between the knives. These relatively long knives are easily sibject to damage. The modern, more functional, and more reliable labyrinth seals consist of sturdy, closely spaced lands. Some labyrinth seals are shown in Fig. 10-107. Figure 10-107 7 is the simplest form of the seal. Figure... 

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